Maternal postpartum depression is a common complication of childbirth that affects the whole family. Fathers’ greater involvement in childcare can buffer children from the negative effects of mothers’ depression, and aid in mothers’ recovery, so it is important to understand under what conditions fathers become more or less involved when mothers are depressed. Prior research has supported both a compensation hypothesis, whereby fathers compensate for the effects of mothers’ depression on mothers’ parenting by being more involved in parenting, and a spillover hypothesis, whereby mothers’ negative emotionality causes fathers to pull back from family life and be less involved in childcare. The present study addressed three factors that could moderate the relationship between mothers’ postpartum depression and fathers’ involvement in childcare: the timing and duration of mothers’ postpartum depression, the presence of mothers’ comorbid anxiety symptoms, and whether couples work the same shift or opposite-shifts from each other. These questions were addressed using a sample of 182 dual-earner, working-class, married or cohabiting couples having their first child. Findings supported a compensation effect when mothers’ were depressed at one time point, but not two, with a stronger interaction between early and later maternal depression for couples working opposite-shifts than those working same-shifts. Comorbid anxiety moderated the effect of maternal depression on father involvement at 1-month postpartum, with fathers more involved when mothers were depressed with low anxiety, and less involved when mothers were depressed with higher anxiety. Implications for research and practice are discussed.